Types of Thermometer

Galileo thermometer.A Galileo thermometer (or Galilean thermometer), named after Italian physicist Galileo Galilei, is a thermometer made of a sealed glass cylinder containing a clear liquid and a series of objects whose densities are such that they rise or fall as the temperature changes. By definition, Galileo's thermometer is actually a thermoscope, not a thermometer.

Gas thermometer A gas thermometer measures temperature by the variation in volume or pressure of a gas. One common apparatus is a constant volume thermometer. It consists of a bulb connected by a capillary tube to a manometer. The bulb is filled with a gas such that the volume of the gas in the bulb remains constant. The volume is related to temperature by k, known as Charles's Law . The pressure of the gas in the bulb can be obtained by measuring the level difference in the two arms of the manometer. Gas thermometers are often used to calibrate other thermometers. Alcohol thermometer

The Alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer, and functions in a similar way. But unlike mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate away fairly quickly. For the working temperature range, themeniscus or interface between the liquid is within the capillary. With increasing temperature, the volume of liquid expands and the meniscus moves up the capillary. The position of themeniscus shows the temperature against an inscribed scale.

Infrared thermometerInfrared thermometers infer temperature using a portion of the thermal radiation sometimes called blackbody radiation emitted by the object of measurement. They’re sometimes called laser thermometers if a laser is used to help aim the thermometer, or non-contact thermometers to describe the device’s ability to measure temperature from a distance. By knowing the amount of infrared energy emitted by the object...

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...Noah Borel
Thermometers
A thermometer is a device or instrument used for measuring temperature. There are many different types of thermometers; however each one is based on a physical property of a thermometric (temperature measuring) substance that differs in a measurable way with temperature. Some of the physical properties that vary with temperature are volume, resistance and color. A physical property that increases or decreases with temperature can be used to measure temperature. This is called a thermometric property.
Liquid-In-Glass Thermometers
There are two types of liquid-in-glass thermometers: 1) Mercury-In-Glass Thermometers 2) Alcohol-In-Glass Thermometers.
A liquid in glass thermometer uses mercury or alcohol as its thermometric substance. Its thermometric property is volume and it is used to measure the temperature by allowing the mercury or alcohol to expand or contract in the capillary tube as temperature rises or decreases. I.e. an increase in temperature equals an increase in volume while a decrease in temperature equals a decrease in volume.
A mercury-in-glass thermometer has a range of -39oC to 360oC while an alcohol-in-glass thermometer has a range of -112o C to 78o C.
Noah Borel
Here are some advantages and disadvantages of mercury-in-glass...

...
Thermometer is the device used to measure temperature.
The extremely fine tube (narrow bore) of a thermometer is called a capillary.
The boiling point of water (or condensing point of steam) is 100oC or 212oF or 373 K.
The freezing point of water (or melting point of ice) is 0oC or 32oF or 273 K.
These temperatures are typically used in the calibration of thermometers and are known as the fixed points.
The temperature range that is typically marked on a laboratory thermometer is −10oC to 110oC.
Thermometric liquids are those that are used in thermometers.
Some examples of such liquids are mercury and alcohol.
The thermometric fluid used by Galileo Galilei in his thermometer was air.
Alcohol, which is used as a thermometric liquid, has the following characteristic properties :
1. Alcohol has a very low freezing point of about −112oC and hence is suitable in thermometers to record very low temperatures.
2. Alcohol has a low boiling point of about 78oC and therefore cannot be used to measure high temperatures.
3. Alcohol can be colored brightly (by adding a dye, generally red) and then it is clearly visible through glass.
4. Alcohol expands more than mercury.
5. Alcohol is fairly inexpensive.
6. Alcohol wets glass.
7. Alcohol is not a good conductor of heat.
Mercury, which is used as a thermometric liquid, has the following characteristic properties :...

...Thermometers measure temperature, by using materials that change in some way when they are heated or cooled.
What can be considered the first modern thermometer, the mercury thermometer with a standardized scale, was invented by Daniel Gabriel Fahrenhei[->0]t in 1714.
The Celsius temperature scale is also referred to as the "centigrade" scale. Centigrade means "consisting of or divided into 100 degrees". In 1742, the Celsius scale was invented by Swedish Astronomer Anders Celsius[->1].
Lord Kelvin[->2] took the whole process one step further with his invention of the Kelvin Scale in 1848. The Kelvin Scale measures the ultimate extremes of hot and cold.
When you look at a regular outside bulb thermometer, you'll see a thin red or silver line that grows longer when it is hotter. The line goes down in cold weather. This liquid is sometimes colored alcohol but can also be a metallic liquid called mercury. Both mercury and alcohol grow bigger when heated and smaller when cooled. Inside the glass tube of a thermometer, the liquid has no place to go but up when the temperature is hot and down when the temperature is cold. Numbers are placed alongside the glass tube that mark the temperature when the line is at that point.
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The quartz thermometer is a high-precision, high accuracy temperature sensor. It measures...

...Temperature and Thermometers
The Temperature of an object is a measure of the hotness or coldness of that object.
An alternative way to think of temperature is to say that “the temperature of an object is a number – on some manmade scale – that indicates the hotness of the object”.
‘Hotness’ in turn is a measure of the kinetic energy of the molecules of the material.
Note: You must use the term ‘hotness’.*
The SI unit of temperature is the Kelvin (K)*
Relationship between degrees Celsius and Kelvin*:
Thermometric Properties
A Thermometric Property is any physical property that changes measurably with temperature.
Note: You must use the term ‘measurably’.
Examples of thermometric properties:
• Length of a column of liquid, e.g. mercury and alcohol thermometers,
• Electrical resistance (see chapter 23),
• Colour (colour ‘strips’ are sometimes used by nurses and placed against a person’s forehead),
• Emf of a thermocouple (emf is a fancy word word for ‘voltage’),
• Volume of gas at constant pressure,
• Pressure of a gas at constant volume.
Disagreement between thermometers
Two different types of thermometer will give slightly different readings at the same temperature.*
This means we need to agree on one particular thermometer to have as a standard.
Practical Thermometers
• Clinical thermometer
• Oven thermometer
•...

...﻿Thermometers: Understand the options
Thermometers come in a variety of styles. Understand the different types of thermometers and how to pick the right thermometer for you.By Mayo Clinic Staff
Choosing the thermometer that's best for your family can be confusing. Here's what you need to know about the most common thermometers.
Digital thermometers
Regular digital thermometers, which use electronic heat sensors to record body temperature, can be used in the rectum, mouth or armpit. The most accurate way to take a child's temperature is to use a digital thermometer, either rectally or orally. Rectal temperatures provide the best readings for infants, especially those 3 months or younger as well as children up to age 3. If you use another type of thermometer to take a young child's temperature and you're in doubt about the results, take a rectal temperature. For older children and adults, oral readings are usually accurate — as long as the mouth is closed while the thermometer is in place. Armpit readings tend to be less accurate than rectal and oral readings.
Pros. Most digital thermometers can record temperatures from the mouth, armpit or rectum — often in a minute or less. A digital thermometer is appropriate for newborns, infants, children and adults....

...VIT Emblem
SCHOOL OF ELECTRICAL ENGINEERING
VIT University
“ AUDIBLE THERMOMETER”
PROJECT REPORT
For
Project Based learning (PBL)
In
Biomedical Instrumentation
Winter 2012-2013
by
B.SRIKAR SUDARSAN
M.SARATH KUMAR
S.YOGESH RAJ
Under the Guidance of
Prof.M.Monica Subashini
Guide
ACKNOWLEDGEMENTS
We have put efforts in this project. However, it would not have been possible without the kind support and help of individuals and organization. We would like to extend my sincere thanks to all of them.
We are highly indebted to Prof.Monica subashini for the guidance and constant supervision as well as for providing necessary information regarding the project &amp; also for the support in completing the project.
We would like to express our gratitude towards the SELECT and lab assistants for providing us with costly apparatus which helped us in completion of this project.
We would like to express our special gratitude and thanks to VIT University for giving us such an opportunity and facilities.
10BEI0055
10BEI0047
10BEI0042
ABSTRACT
The objective of our project was to build a Independent audible thermometer, which can speak the body temperature of a person. Our original goal was to build both software and hardware setup of the audible thermometer. We have already finished the software setup and we are currently working on the hardware, which we couldn’t complete because...

...MEDICAL THERMOMETER
Medical thermometers are used for measuring human body temperature, with the tip of the thermometer being inserted either into the mouth under the tongue (oral or sub-lingual temperature), under the armpit (axillary temperature), or into the rectum via the anus (rectal temperature).
CLASSIFICATION BY TECHNOLOGY
Liquid-filled
The traditional thermometer is a glass tube with a bulb at one end containing a liquid which expands in a uniform manner with temperature. The tube itself is narrow (capillary) and has calibration markings along it. The liquid is often mercury, but alcohol thermometers use a colored alcohol. Medically, a maximum thermometer is often used, which indicates the maximum temperature reached even after it is removed from the body.
To use the thermometer, the bulb is placed in the location where the temperature is to be measured and left long enough to be certain to reach thermal equilibrium—typically three minutes. Maximum-reading is achieved by means of a constriction in the neck close to the bulb. As the temperature of the bulb rises, the liquid expands up the tube through the constriction. When the temperature falls, the column of liquid breaks at the constriction and cannot return to the bulb, thus remaining stationary in the tube. After reading the value, the thermometer must be reset by repeatedly swinging it...